omy.Utils.OData.Generators 0.0.1

Utils.OData.Generators

Utils.OData.Generators offers a Roslyn source generator that materializes entity classes and helpers for contexts derived from Utils.OData.ODataContext. It targets .NET 9 and consumes EDMX metadata so OData payloads can be accessed through strongly typed models.

Features

• Locates partial classes inheriting from ODataContext and inspects their base constructor calls.
• Loads EDMX definitions from relative paths or HTTP/HTTPS endpoints at build time.
• Generates nested entity classes with nullable support, XML documentation, and [Key] attributes for primary keys.
• Reports diagnostics when metadata cannot be found, downloaded, or deserialized (ODATA001–ODATA003).
• Produces deterministic source files that play nicely with incremental builds and IDE navigation.

Prerequisites

1. Reference Utils.OData in your project.
2. Add Utils.OData.Generators as an analyzer reference so MSBuild executes the generator.
3. Create a partial context that calls an ODataContext base constructor with the EDMX location.

Usage example

using Utils.OData;

public partial class ProductContext : ODataContext
{
    public ProductContext() : base("metadata/Products.edmx") { }
}

When the project is built, the generator reads metadata/Products.edmx, produces partial classes such as ProductContext.Product, and populates each property with the correct .NET type. The generated members can then be consumed through the LINQ provider:

var context = new ProductContext();
var query = context.Products.Where(p => p.Price > 5).OrderBy(p => p.Name);

If the EDMX path is wrong or the file cannot be parsed, the generator raises diagnostics so the issue is caught during compilation instead of at runtime.

Examples

Extending generated entities

Entities are emitted as partial classes, allowing domain-specific behavior to be added alongside the generated members.

public partial class ProductContext
{
    public partial class Product
    {
        public bool IsLowStock => UnitsInStock < 5;
    }
}

Because Product is a partial class, additional properties and helper methods seamlessly coexist with generated properties while keeping custom logic separate from tooling output.

Consuming remote metadata

You can point the base constructor to a remote EDMX URL; the generator downloads and caches the metadata during build.

public partial class RemoteContext : ODataContext
{
    public RemoteContext() : base("https://example.com/$metadata") { }
}

When network retrieval fails, diagnostic ODATA002 highlights the HTTP issue, while malformed payloads trigger ODATA003, making problems explicit to developers before deployment.

Handling multiple models

Large solutions often require multiple contexts. Simply declare additional partial classes, each referencing a different EDMX location, and the generator will emit isolated entity hierarchies per context.

public partial class SalesContext : ODataContext
{
    public SalesContext() : base("metadata/Sales.edmx") { }
}

public partial class SupportContext : ODataContext
{
    public SupportContext() : base("metadata/Support.edmx") { }
}

Each context receives its own ODataQueryable<T> properties and entity types, ensuring models stay isolated even when they share the same assembly.

Navigation properties and expansions

Generated entities include navigation properties mapped from the EDMX metadata.

using System.Linq;
using Utils.OData;

public partial class ProductContext : ODataContext
{
    public ProductContext() : base("metadata/Products.edmx") { }
}

var context = new ProductContext();
var query = context.Products
    .Where(p => p.Supplier.City == "Paris")
    .Expand(p => p.Supplier)
    .Select(p => new { p.Name, Supplier = p.Supplier.Name });

The LINQ provider recognizes the generated navigation properties and emits $expand segments automatically when needed.

Partial classes for validation

Because entities are partial classes, domain validation rules can live alongside generated members without being lost during rebuilds.

using System;

public partial class ProductContext
{
    public partial class Product
    {
        partial void OnNameChanging(string? value)
        {
            if (string.IsNullOrWhiteSpace(value))
            {
                throw new ArgumentException("A product requires a non-empty name.");
            }
        }
    }
}

The generator respects existing partial methods and only emits missing declarations, so custom validation hooks run whenever the entity property changes.

Diagnostics reference

Diagnostics surfaced by the generator can be acted upon quickly during development:

Keeping this table handy speeds up troubleshooting when metadata moves or services change.